Section 1.6 defines the rendering tree, in part "element whose 'display'
property is set to 'none [*** missing closing quote ***] .. and their
children ... not part of the Rendering tree (and thus do not get rendered)".
Section 11.15 has language for each of the gradient types saying that
"'linearGradient' elements are availabe fro referencing even when the
'display' property on the 'linearGradient' element or any of its
ancestors is set to none". Is this meant to specify that a gradient
should still be drawn if it or an ancestor has "display: none", or that
it should not be considered an invalid IRI when referenced per 11.2?
Please clarify the language to make it clear which interpretation is
intended.